Anritsu Company in collaboration with Fujikura Ltd., has measured inter-core crosstalk in weakly coupled multi-core optical fibers using multiple methods and has confirmed that the results are equivalent. Both companies will present their results at the international OptoElectronics and Communications Conference(OECC 2025) to be held in Sapporo, Japan, from June 29 to July 3, 2025.

With the growing adoption of artificial intelligence (AI) and cloud services, the demand for higher transmission capacity in optical submarine cables and data center interconnects is rapidly increasing. Today’s optical communications rely on single-mode fiber (SMF) and advanced signal optimization technologies to achieve high data throughput. However, as the transmission capacity per fiber continues to grow, these technologies are approaching their physical and performance limits.

Consequently, recent R&D has focused on weakly coupled multi-core optical fiber with multiple independent cores in a single optical fiber. While this type of fiber significantly increases transmission capacity, inter-core crosstalk – caused by interference resulting from light leakage between each core – degrades the quality of transmission. This varies not only due to the optical fiber design and manufacturing but also depending on the installation conditions, requiring evaluation of inter-core crosstalk in field conditions. Although various companies and research institutions have proposed different methods for measuring inter-core crosstalk, the measured results from each method have not yet been adequately validated.

In the presented comparative evaluation, Anritsu, in collaborating with Fujikura, measured inter-core crosstalk using four methods: two using optical power meters, and two using Anritsu's OTDR (Optical Time Domain Reflectometer) for measuring optical fiber loss and reflection. The evaluated four-core weakly coupled multi-core optical fiber manufactured by Fujikura features a standard cladding diameter of 125 µm. The measured results from each measurement method were all within ±1.0 dB at 1550 nm. Consequently, any of these four measurement methods can be chosen according to the weakly coupled multi-core optical fiber application scenario, such as R&D, Manufacturing, and Installation and Maintenance (I&M), with assured consistent correlation regardless of which method is used. Furthermore, these results will assist with future standardization of weakly coupled multi-core optical fiber.

Anritsu will continue to contribute to the practical implementation of next-generation optical communications technology by providing test solutions for weakly coupled multi-core optical fibers.

Presentation at OECC 2025 (Sapporo Convention Center)

• 15:15 to 15:30 on July 1, 2025
• Session: O3. Optical Fibers, Cables, Fiber Devices and Fiber Sensing
  Title: Comparison of crosstalk measurement methods for weakly-coupled multicore fibers